Incidence Of Tick-borne Encephalitis Research Articles

TBE in Denmark

Since the 1950s tick-borne encephalitis (TBE) has been known to be endemic in Denmark but only on the island of Bornholm. Bornholm is situated east of mainland Denmark, south of Sweden (Figure 3) and has a different fauna and flora from the rest of Denmark. Bornholm has about 45,000 inhabitants, but about 500,000 tourists visit the island every year. Freundt carried out a serosurvey during 1958–19621 and found TBE antibodies in 1.4% of blood donors and 30% of woodworkers on Bornholm but no antibodies in subjects living in mainland Denmark. In 1963, Freundt found that 8 of 12 patients admitted to the hospital with acute meningoencephalitis of unknown etiology during 1951–1960 had antibodies to tick-borne encephalitis (TBEV).2 In 2000, TBE was rediscovered on Bornholm, where a retrospective study covering the period 1994–2002 (7 years) identified 14 TBE cases; 2 cases were tourists and 12 were inhabitants of Bornholm, giving an incidence of 3.81 per 100,000 inhabitants.3 At least 5 patients (37.7%) got permanent sequelae. In addition, 32 forest workers on Bornholm were tested in 2000, and 20% had IgG antibodies but never symptoms. This is similar to the finding of Freundt in 1960. It was concluded that the data did not provide evidence of an increase in incidence of TBE. Ticks (Ixodes ricinus) from Bornholm were investigated for TBEV in 2000 and 2% were found to be infected.4 Since 2001 an average of 2.5 (range 1–8) TBE cases per year have been reported in Bornholm (Figure 1).

Trends in Epidemic Process Development of Tick-Borne Encephalitis in the Russian Federation, Laboratory Diagnosis, Prophylaxis and Forecast for 2021

Tick-borne encephalitis is a natural-focal infection damaging central nervous system, caused by the similarly-named virus transmitted by several species of ixodic ticks. Natural foci of tick-borne encephalitis (TBE) are widely spread in the forest and forest-steppe landscape zones of the temperate climate belt in the vast territory of Eurasia from the Atlantic to the Pacific Ocean. New TBE-endemic territories have been recently identified in Japan, the Netherlands, and in the UK – in 2019. The increasing risk of infection due to the development of tourism and visits to natural foci of TBE became a public health issue of international concern. The aim of the study is to identify modern features of TBE incidence dynamics in the Russian Federation, the state of laboratory diagnostics and prevention and to predict the incidence for 2021. The paper shows that there is a persistent downward trend in TBE-cases in Russia, which is observed through the past few years. The characteristic feature of the epidemic season-2020 was a significant reduction in the incidence of TBE: 989 cases were registered in 33 constituent entities of the Russian Federation (morbidity rate – 0.67 per 100 000 of the population). The sharp decrease of TBE cases in 2020 as compared to 2019 against the background of a decrease in vaccination can be explained, along with natural factors, by the introduction of restrictive measures during the COVID-19 epidemic. The paper also reflects the dynamics of morbidity, seeking the medical services because of tick bites, the infection rate of the carrier, the scope of vaccination, seroprophylaxis, acaricide treatments. The coverage of express-diagnostic tests of ticks for markers of associated pathogens and its availability for the population are presented. It is recognized that the epidemiological situation on TBE in the Russian Federation remains unfavorable. It demands constant attention on the part of healthcare organizations and Federal Service for Surveillance in the Sphere of Consumers Rights Protection and Human Welfare, as well as management decision making aimed at further decrement in TBE incidence through the improvement of prevention measures, specifically in the entities that are characterized by high TBE incidence. The situation requires monitoring of natural foci of infection, enhancement of prophylaxis and treatment of TBE. The paper provides the forecast of TBE incidence for 2021 and values of the 95 % confidence range of the indicator fluctuation, taking into account the presence or absence of trends in its changes in the territory of federal districts and constituent entities of the Russian Federation in 2011–2020.

Epidemiology of tick-borne encephalitis in Poland (2010-2019) and the impact of the COVID-19 pandemic on the notified incidence of the disease.

Tick-borne encephalitis (TBE) is endemic in many parts of Eurasia including countries previously considered to be free from the disease. The incidence of TBE is changing owing to various ecological and climatic factors. The factors influencing the variability of the number of TBE cases are still under investigation. In 2020 the new coronavirus SARS-CoV-2 emerged causing COVID-19 pandemic. Governments have reorganized health care systems to contain a surge of COVID-19 cases and avoid hospital overload. Moreover, new measures have modified several aspects of social habits leading to a change in the incidence of numerous diseases. We aimed to evaluate the epidemiology of TBE in the last decade (2010-2019) and to demonstrate the impact of the surge of SARS-CoV-2 infections on the TBE incidence as reported to a national surveillance database. We performed the analysis of the TBE notification from the epidemiologic reports in the years 2010-2019 and in the pandemic year 2020 at a national and regional level in Poland. We included data from two infectious disease departments located in the most TBE-prevalent province of Poland. Most cases of TBE occur in two provinces of Northeastern Poland from May to December. The increasing temporal trend occurred in Poland in 2016-2017. The increased number of cases of COVID-19 coincided with a reduction of the number of the reported TBE cases in 2020. Tick-borne encephalitis virus activity in Poland is invariably concentrated in endemic regions of Northeastern Poland fluctuating considerably from year to year. The decrease of TBE incidence with surge of COVID-19 patients conceivably resulted from underreporting due to limited access to specialized diagnostics. In endemic areas, TBE should be included in the differential diagnostics in all the cases when the central nervous system infection in suspected.

Оценка эпидемической ситуации по заболеваемости клещевым риккетсиозом и клещевым энцефалитом населения Алтайского края в 2000-2019 гг.

The article presents the results of a study carried out in relation to the epidemic situation in terms of the incidence of one of the topical representatives of tick-borne natural focal infections among the population of the Altai Territory in the period from 2000 to 2019 – tick-borne rickettsiosis and tick-borne encephalitis. An assessment of the prevalence of these infections among certain age and social groups of the region's population is presented. Using GIS technologies and the method of sigma deviations, the spatial prevalence of current infections in the territory of the region was estimated and regions with high, medium and low, for the Altai Territory, incidence of tick-borne encephalitis and tick-borne rickettsiosis during the study period were identified. The results of the assessment of preventive measures carried out in the region aimed at reducing the incidence of current infections among the local population – vaccine prophylaxis, seroprophylaxis and acaricidal treatments of territories are presented.

Assessment of the Implemented Strategy for Ensuring the Epidemiological Control of the Incidence of Tick-Borne Encephalitis and Rickettsiosis in the Altai Territory in 2000-2019

Assessment of the Implemented Strategy for Ensuring the Epidemiological Control of the Incidence of Tick-Borne Encephalitis and Rickettsiosis in the Altai Territory in 2000-2019

The epidemiology, clinical presentation, and predictors of severe Tick-borne encephalitis in Lithuania, a highly endemic country: A retrospective study of 1040 patients.

IntroductionIn recent decades, the incidence of Tick-borne encephalitis (TBE) has been increasing and posing a growing health problem because of the high costs to the healthcare system and society. The clinical manifestations are well studied but there is a lack of research analyzing the severity of the disease.ObjectiveThe aim of this study was to analyze the epidemiology and clinical presentation of severe TBE, to identify the predictors for a severe disease course, and also predictors for meningoencephalomyelitic and severe meningoencephalitic/encephalitic forms.MethodsA retrospective study was conducted in the Center of Infectious Diseases and the Center of Neurology at Vilnius University Hospital Santaros Klinikos in the years 2005–2017 to describe the clinical and epidemiological features of TBE in adults.Results1040 patients were included in the study. A total of 152/1040 (14.6%) patients had a severe course. The highest proportion of severe cases, reaching 41.2%, was reported in the 70–79 year-old age group. A total of 36/152 (23.7%) severe patients presented meningoencephalomyelitis. Myelitic patients were older, were frequently infected in their living areas, and usually reported a monophasic disease course compared with severe meningoencephalitic/encephalitic patients. Severe meningoencephalitic/encephalitic patients, compared with non-severe meningoencephalitic/encephalitic, were older, less often noticed the tick bite, and often had a monophasic course. The sequelae on discharge were observed in 810/1000 (81%) of patients.ConclusionsThe prognostic factors associated with a severe disease course and severe meningoencephalitic form are: older age, comorbidities, a monophasic course, a fever of 40˚C and above, CRP more than 30 mg/l, CSF protein more than 1 g/l, delayed immune response of TBEV IgG, pathological findings in CT. Age above 60 years, presence of CNS disease, bulbar syndrome, pleocytosis 500x106/l and above, and delayed immune response of TBEV IgG are predictors of the most severe myelitic form.

The Red Fox (Vulpes vulpes) as Sentinel for Tick-Borne Encephalitis Virus in Endemic and Non-Endemic Areas.

Tick-borne encephalitis (TBE) is one of the most important viral zoonosis caused by a neurotropic arbovirus (TBEV). In Germany, TBE is classified as a notifiable disease with an average of 350 autochthonous human cases annually. The incidence-based risk assessment in Germany came under criticism because every year, a number of autochthonous human TBE cases have been detected outside of the official risk areas. Therefore, it is necessary to find additional parameters to strengthen TBEV surveillance. The aim of this study was to examine red foxes as sentinels for TBE. Thus far, there are no published data about the sensitivity and specificity for serological methods testing fox samples. Hence, we aimed to define a system for the screening of TBEV-specific antibodies in red foxes. A total of 1233 fox sera were collected and examined by ELISA and IIFA and confirmed by micro-NT. The overall seroprevalence of antibodies against TBEV in red foxes from Germany confirmed by micro-NT was 21.1%. The seroprevalence differed significantly between risk (30.5%) and non-risk areas (13.1%), with good correlations to local TBE incidence in humans. In conclusion, serological monitoring of red foxes represents a promising surrogate marker system and may even determine unexpected TBEV foci in regions currently regarded as non-risk areas.

A Retrospective Epidemiological Study of Tick-Borne Encephalitis Virus in Patients with Neurological Disorders in Hokkaido, Japan.

Tick-borne encephalitis (TBE) is a zoonotic disease that usually presents as a moderate febrile illness followed by severe encephalitis, and various neurological symptoms are observed depending on the distinct central nervous system (CNS) regions affected by the TBE virus (TBEV) infection. In Japan, TBE incidence is increasing and TBEV distributions are reported in wide areas, specifically in Hokkaido. However, an extensive epidemiological survey regarding TBEV has not been conducted yet. In this study, we conducted a retrospective study of the prevalence of antibodies against TBEV in patients with neurological disorders and healthy populations in a TBEV-endemic area in Hokkaido. Among 2000 patients, three patients with inflammatory diseases in the CNS had TBEV-specific IgM antibodies and neutralizing antibodies. The other four patients diagnosed clinically with other neurological diseases were positive for TBEV-specific IgG and neutralizing antibodies, indicating previous TBEV infection. In a total of 246 healthy residents in a TBEV-endemic region, one resident had TBEV-specific antibodies. These results demonstrated undiagnosed TBEV infections in Japan. Further surveys are required to reveal the actual epidemiological risk of TBE and to consider preventive measures, such as a vaccine program, for the control of TBE in Japan.

Game Animal Density, Climate, and Tick-Borne Encephalitis in Finland, 2007-2017.

Tick-borne encephalitis (TBE) is an endemic infection of public health importance in Finland. We investigated the effect of ecologic factors on 2007–2017 TBE trends. We obtained domestic TBE case data from the National Infectious Diseases Register, weather data from the US National Oceanic and Atmospheric Administration, and data from the Natural Resources Institute in Finland on mammals killed by hunters yearly in game management areas. We performed a mixed-effects time-series analysis with time lags on weather and animal parameters, adding a random effect to game management areas. During 2007–2017, a total of 395/460 (86%) domestic TBE cases were reported with known place of exposure and date of sampling. Overall, TBE incidence increased yearly by 15%. After adjusting for the density of other animals and minimum temperatures, we found thatTBE incidence was positively associated with white-tailed deer density. Variation in host animal density should be considered when assessing TBE risks and designing interventions.

Analysis of Tick-borne Encephalitis vaccination coverage and compliance in adults in Switzerland, 2018

BackgroundOverall incidence and geographic range of Tick-borne Encephalitis (TBE), a vaccine preventable infection, have steadily increased in Switzerland over the last 50 years. While fully subsidized vaccination has been recommended in many areas for well over a decade, vaccine coverage and variables associated with vaccination compliance among Swiss adults are poorly understood. MethodsIn 2018 we conducted a national, cross-sectional survey of vaccination cards evaluating TBE vaccination coverage and compliance among adults (18-79) in Switzerland. ResultsNationwide TBE vaccination coverage was 41.7% (range 14.3% to 60.3%) for 1 dose and 32.9% (range 8.4% to 50.4%) for a complete primary series (3 doses). There was a significant correlation between average disease incidence by canton (2009-2018) and vaccine coverage at both 1 and 3 doses. Of the overall population, 9.5% had received at least one TBE booster vaccination with large regional coverage variation. We estimated that 23% of adults in Switzerland would be protected from infection based on their vaccination history and 135 (95% CI: 112-162) TBE cases were prevented in 2018. Individuals reporting previous experience with tick-associated health problems, those frequently in nature or those with “high” perceived risk of contracting TBE, were significantly more likely to have received at least one vaccine dose, indicating a positive impact of awareness on vaccination compliance. We also calculated a TBE incidence rate of 6.83/100,000 among the unvaccinated adult population in Switzerland and estimated vaccine effectiveness at 91.5% (95% CI: 90.9-92.0%). ConclusionsThese findings provide an important reference for TBE vaccination levels in Switzerland and further suggest that public health interventions promoting knowledge of TBE health impacts and risk factors may be beneficial in improving TBE vaccination coverage but should be tailored to account for heterogeneity in vaccine uptake.

Operational TBE incidence forecasts for Austria, Germany, and Switzerland 2019–2021

In spring 2019, forecasts of the incidence of tick-borne encephalitis (TBE) for the next 2 years, i.e. 2019 and 2020, were made for the first time. For this purpose, negative binomial regression models with 4–5 predictors were fitted to the time series of annual human TBE incidences from Austria, Germany, and Switzerland. The most important predictor for TBE incidences is the fructification index of the European beech (Fagus sylvatica) 2 years prior as a proxi for the intensity of the TBE virus transmission cycle. These forecasts were repeated in spring 2020 after the updated predictors and the confirmed TBE cases for 2019 became available. Forecasting TBE incidences for 2020 and 2021 results in 156 ± 19 and 131 ± 23 TBE cases for Austria, 663 ± 95 and 543 ± 112 TBE cases for Germany as well as 472 ± 56 and 350 ± 62 TBE cases for Switzerland. The newly implemented operational TBE forecasts will be verified every year with confirmed TBE cases. An initial verification for 2019 demonstrates the high reliability of the forecasts.

Travel restrictions and lockdown during the COVID-19 pandemic-impact on notified infectious diseases in Switzerland.

Based on notification data the impact of the COVID-19 lockdown in Switzerland was assessed. While the incidence of tick-borne encephalitis almost doubled as compared to 2016-2019, a reduction in all other infectious diseases was recorded. The lowest reduction rates (<25%) were noted for legionellosis, hepatitis A, chlamydia infection and gonorrhoea.

Ecological and epidemiological characteristics of tick-borne encephalitis in St. Petersburg

Here, we provide an analysis on 1996–2016 St. Petersburg tick-borne encephalitis (TBE) epidemiological and ecological data. In particular, two main TBE transmission vectors were observed in St. Petersburg: Ixodes persulcatus Ixodes ricinus. TBE tick contamination was 0.61% as shown by ELISA and polymerase chain reaction data. It is found that number of subjects seeking for medical aid due to tick bites rises, whereas TBE incidence declines. In particular, a mean 1996–2002 vs. 2010–2016 tick-bite incidence rate increased from 141.9 up to 288.9, respectively. Despite that the Leningrad region is a major area for TBE spread, however, a risk of exposure to tick bites as well as TBE infection exists even in the city of St. Petersburg. In connection with this, around 1,000 subjects undergo tick bites within the city limits. Moreover, whereas a 1996–2002 mean TBE incidence rate was 1.66, it decreased in 2010–2016 down to 1.17. A peak TBE incidence was documented in St. Petersburg Kurortny, Pushkinsky and Primorsky districts. In addition, males vs. females suffered from TBE at higher frequency in Russian Federation, with its peak incidence rate being reported in children under 14 that differs St. Petersburg from the most of other regions in the Russian Federation. A seasonal distribution of TBE cases in St. Petersburg does not differ from that one for the remainder of Russian regions, which displays a spring-summer seasonality lasting from April to September. Of note, 1996–2016 St. Petersburg TBE mortality was 1.37%. A coverage of TBE vaccinated population tends to rise but still remains at low level (0.25–0.58%). Lack of reported TBE cases in occupationally threatened human cohorts evidences about efficient preventive measures. Detection of TBE virus-specific serum antibodies in 5.0% apparently healthy and unvaccinated residents in St. Petersburg significantly complements the official TBE recording data and provides a more accurate understanding of its actual spread.

Tick-borne Encephalitis in the Yaroslavl Region in the Context of Planned Vaccine Prevention

Relevance . In the Yaroslavl region, the Central Federal District of Russia, endemic for tick-borne encephalitis (TBE), specific TBE vaccination has been routinely carried out for more than 20 years. Therefore, the evaluation of the results of long-term universal immunoprophylaxis the population has a practical and scientific interest. Purpose : To study the epidemiology of tick-borne encephalitis in the context universal vaccine in 2008-2019. Results and discussion . According to the results of long-term immunization, by 2019 19.1% of the population was vaccinated, while vaccine coverage for the children living in endemic areas of the region reaches 68-83%. The article noted a 2.9-fold decrease in the incidence of TBE in 2013-2018 compared with 2008-2012. The average long-term level was 0.69 per 100 ths people. TBE was recorded among the unvaccinated population, mild febrile forms prevailed - 56.8%, however, the proportion of focal forms of the disease remained high (36.3%). Deaths from TBE in the period from 2013-2018 did not have. Thus, in the absence of specific treatment for TBE, vaccine prophylaxis is of great medical and social importance for the Yaroslavl region endemic for TBE. Conclusion. Vaccine coverage in the population of Yaroslavl region, children living in endemic areas and natural immunization in natural foci of TBE contributed to the formation of a significant level of collective immunity of the population to TBE, reducing the incidence of in the last 5 years.

Analysis of the epidemic situation of tick-borne viral encephalitis in the Republic of Altai in 2000-2017

Introduction. The Republic of Altai is one of the regions of the Siberian Federal District endemic for tick-borne encephalitis with high altitude mountain belts with characteristic landscape and climatic conditions. The purpose of this study is to analyze the epidemiological situation of tick-borne encephalitis in the Republic of Altai from 2000 to 2017. Material and methods. In conducting a retrospective epidemiological study, data from sanitary-epidemiological and medical services for 2000-2017 were used. Statistical data processing was carried out with the software “Statistica 12.0”, the construction and analysis of cartograms - with the software ArcGIS. Results. The average long-term incidence rate of this infection in the period from 2000 to 2017 amounted to 21.7 ± 0.76 0/0000, which is 2.2 times higher than the similar indexby for the SFO (10.1 ± 0.23 0/0000). The number of persons affected by tick infestation in the period from 2000 to 2017 increased 3.5 times from 517.7 ± 15.95 0/0000 to 1810.5 ± 28.62 0/0000, respectively (p &lt;0.001). Ranking on the level of the average long-term incidence allowed identifying three groups of the potential risk of infection of the population. Discussion. The factor analysis revealed the presence of an inverse correlation between the incidence of tick-borne encephalitis and the levels of seroprophylaxis (r = -0.93), acaricidal treatments (r = -0.95), vaccination (r = -0.10). The calculated levels of these factors were determined according to the results of the construction of spatial models of their mutual influences, capable of reducing the number of cases in the region to 6 per year. Conclusion. An analysis of the epidemic situation based on factor analysis and spatial modeling of the mutual influence of factors made it possible to determine the necessary volumes of preventive measures to reduce the incidence of the population to a given level. Such a calculation may be applicable in an endemic region to ensure the medical and economic effectiveness of preventive measures.

Analysis of the epidemic situation of tick-borne viral encephalitis in the Republic of Altai in 2000-2017

Introduction. The Republic of Altai is one of the regions of the Siberian Federal District endemic for tick-borne encephalitis with high altitude mountain belts with characteristic landscape and climatic conditions. The purpose of this study is to analyze the epidemiological situation of tick-borne encephalitis in the Republic of Altai from 2000 to 2017. Material and methods. In conducting a retrospective epidemiological study, data from sanitary-epidemiological and medical services for 2000-2017 were used. Statistical data processing was carried out with the software “Statistica 12.0”, the construction and analysis of cartograms - with the software ArcGIS. Results. The average long-term incidence rate of this infection in the period from 2000 to 2017 amounted to 21.7 ± 0.76 0/0000, which is 2.2 times higher than the similar indexby for the SFO (10.1 ± 0.23 0/0000). The number of persons affected by tick infestation in the period from 2000 to 2017 increased 3.5 times from 517.7 ± 15.95 0/0000 to 1810.5 ± 28.62 0/0000, respectively (p &lt;0.001). Ranking on the level of the average long-term incidence allowed identifying three groups of the potential risk of infection of the population. Discussion. The factor analysis revealed the presence of an inverse correlation between the incidence of tick-borne encephalitis and the levels of seroprophylaxis (r = -0.93), acaricidal treatments (r = -0.95), vaccination (r = -0.10). The calculated levels of these factors were determined according to the results of the construction of spatial models of their mutual influences, capable of reducing the number of cases in the region to 6 per year. Conclusion. An analysis of the epidemic situation based on factor analysis and spatial modeling of the mutual influence of factors made it possible to determine the necessary volumes of preventive measures to reduce the incidence of the population to a given level. Such a calculation may be applicable in an endemic region to ensure the medical and economic effectiveness of preventive measures.

Long-term monitoring of tick-borne viral encephalitis and tick-borne borreliosis in the Komi Republic

Our study was aimed at analyzing data combining objective epidemiological, zoological and entomological research intended to determine the environmental and epidemiological patterns of tick-borne encephalitis (TBE) and Lyme borreliosis (LB) foci, as well as the role of anthropogenic factors in epidemic manifestations to improve anti-epidemic activities. Long-term data on the abundance of ticks flagged from vegetation in various districts of the Komi Republic (RK) have been analyzed. The prevalence of tick-borne encephalitis virus (TBEV) and Borrelia burgdorferi (agent of LB) in ticks picked from vegetation, humans and domestic animals in various districts of the RK was measured by using enzyme-linked immunosorbent assay and polymerase chain reaction (PCR-ELISA). In addition, the data on 1994–2017 tick-bite incidence in RK, 1970–2017 TBE incidence, and 1997–2017 LB incidence were also examined and correlated with the impact of forest transformation on the TBE incidence. The rise of tick population in the southern districts of RK and its northward expansion were noted. It is also shown that the RK territory, where tick bites are registered, expanded significantly. Mean annual tick-bite incidence rate in 2006–2017 vs. 1994–2005 timeframe was increased by 4-fold. RK regions where deforestation took place, the tick-bite incidence was increased, and the local TBE incidence elevated distinctly. In recent years, there was a rise in TBEV prevalence in ticks, collected either from vegetation or from humans and animals. In 2006–2017 and 1970–1981, mean annual TBE incidence rate increased by a 11- and 36-fold as compared to that one registered in 1982–1993. In recent years, the most severe focal TBE forms began to be recorded. In 1996–2017, the TBE mortality rate was 2.3%. The main features of LB epidemiology mimic those found in TBEV. In particular, the prevalence of Borrelia burgdorferi in ticks flagged from vegetation increased from 9.5% to 34.7% in 2010 vs. 2017, respectively. A sharp rise in LB incidence rate and profound northward shift for bacterial range, where this infection started to be registered only in recent years, were noted. Both TBE and LB demonstrated marked occupation-related pattern. The need in conducting task-oriented prophylaxis of tick-borne infections is necessitated by taking into account geographic specifics. The RK northern regions should be considered as potentially endemic, where tick bites in human population has recently begun to be reported.

Investigating novel approaches to tick-borne encephalitis surveillance in Sweden, 2010-2017

Tick-borne encephalitis (TBE) is a vaccine-preventable, high-priority disease in Sweden, with increasing incidence. However, surveillance is limited to case reports. We investigated relationships between reported TBE incidence and syndromic surveillance data to determine if these novel data sources could provide earlier indications of disease activity. We retrospectively compared national, weekly (2010−2017) reported TBE incidence to the percentage of TBE-related a) searches on the main Swedish healthcare information website and b) calls to its telehealth service using Spearman’s ρ to determine the most strongly correlated lags. We conducted a sub-analysis (2012−2017) of TBE-related Google Trends queries and compared the number of TBE-related media stories to each novel surveillance dataset. Healthcare website searches for “tbe” and “vaccine” combined, “tbe”, “tick”, and “tick bite” led case data by 12, 8, 7, and 6 weeks, respectively (ρ = 0.87−0.89); telehealth calls led by 4 weeks (ρ = 0.92; all p < 0.001). Correlations and lags for Google Trends and healthcare website searches were fairly similar to each other. In comparison, correlation between the different syndromic surveillance datasets and the number of media stories was lower (ρ = 0.25−0.56). We observed volume discrepancies between TBE incidence and the novel surveillance datasets during some years, particularly for web searches. Syndromic surveillance data were strongly correlated with and preceded case data by 4–12 weeks. Syndromic data may provide advanced awareness and earlier indications of TBE activity, which can improve timing and specificity of public health communications. The use of these data as supplements to notifiable disease data for national planning and preparedness in real-time should be investigated.

Tick-borne encephalitis incidence forecasts for Austria, Germany, and Switzerland

The forecast of human tick-borne encephalitis (TBE) incidence for the next years has been on the research agenda of epidemiologists since the discovery of this tick-borne zoonosis. Based on models to explain the trend as well as the low- and high-frequency oscillations in the Austrian TBE incidence series, TBE forecasts for Austria, Germany and Switzerland are presented here. For this purpose, generalized linear models (GLMs) of type negative binomial regression were calibrated with the TBE incidences of the period 1991–2018 to forecast the TBE incidences 2019 and 2020. The GLMs require only 4–5 predictors, 2 of which are large-scale synchronized over Central Europe and used for all 3 countries. Predictors used include the demographic parameters total population and net migration rate, the Scandinavian index which describes the large-scale atmospheric circulation patterns, the fructification index of the European beech (Fagus sylvatica) 2 years prior as a proxy for the intensity of the TBE virus transmission cycle, and the national TBE vaccination coverage. Since an official time series of TBE vaccination coverage is only available for Austria, the missing TBE vaccination coverages of Germany and Switzerland were reconstructed and presented as the first results. Model verification results in explained variances of 76% for Austria, 84% for Germany, and 89% for Switzerland. Thus, the best model fit was determined for the Swiss GLM which is able to predict the TBE incidence with a root-mean-square error of RMSE = 25 cases (19% of the mean TBE incidence 1991–2018 or 7% of the TBE incidence of 2018). Forecasting TBE incidences for 2019 and 2020 results in 92 ± 12 and 142 ± 26 TBE cases for Austria, 417 ± 71 and 670 ± 168 TBE cases for Germany as well as 235 ± 30 and 465 ± 91 TBE cases for Switzerland.

Genotyping of tick-borne encephalitis and Kemerovo viruses in taiga ticks collected in the Komi Republic

Over the last years, an increasing rate of ixodes tick bites has been registered in the northern regions of the European Russia. In addition, the number of subjects request medical assistance due to tick bites has been dramatically increased in the Komi Republic. In addition, incidence of tick-borne encephalitis was also increased particularly starting since 2009. However, highly limited data on pathogen genetic diversity related to viral tick-borne infections in this region are currently available. Taiga ticks (Ixodespersulcatus) collected from the Komi Republic southern and central part vegetation were examined to identify and genotype tick-borne viruses. Individual ticks were used to identify by RT-PCR viral RNA coupled to tick-borne encephalitis and Kemerovo viruses. Viral genome fragment sequencing allowed to unambiguously identify these viruses. It was found that viral RNA tick-borne encephalitis was detected in 6.8±1.2% individual ticks. Moreover, tick-linked isolate genotyping based on analyzing E protein gene fragment nucleotide sequence derived from tick-borne encephalitis discovered that 35% and 65% isolates belonged to the Far Eastern and Siberian subtype, respectively. In addition, subsequent phylogenetic analysis demonstrated that at least four variants of the Siberian and Far Eastern subtypes of tick-borne encephalitis virus were detected, which were close to the viruses circulating in the Urals and Siberia. In contrast, prevalence of Kemerovo virus in taiga ticks was 0.8±0.2%. Sequencing of Kemerovo virus RNA-dependent RNA polymerase gene fragment showed around 94% homology with the remainder of the Kemerovo virus strains. Phylogenetic analysis of the Kemerovo virus genome fragments demonstrated at least two subtypes circulating in the Komi Republic. Thus, it was suggested that tick-borne encephalitis virus was introduced relatively recently from the Urals and Siberian region into the natural foci of the Komi Republic. Moreover, genetic differences found in Kemerovo virus strains presume for them a longer lasting evolution throughout the natural foci of this region. In addition, a potential role for birds and their ticks in rapid spreading of viral tick-borne infections in the Komi Republic is also discussed. Thus, the data on genetic diversity of the viral agents related to tick-born encephalitis and Kemerovo fever may be useful for improving their diagnostics, prevention and treatment in the Komi Republic.